Well bore packing apparatus



WELL BORE PACKING APPARATUS Filed Dec. 10, 1965 5 Sheets-Sheet 1 INVENTOR.

Nov. 28, 1967 D. E. YOUNG WELL BORE PACKING APPARATUS Filed Dec.

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Afro/9w r D. E. YOUNG WELL BORE PACKING APPARATUS Nov. 28, 1967 Filed Dec. 10, 1965 5 Sheets-Sheet 4 m y Y@ Nov. 28, 1967 D. E. YOUNG WELL BORE PACKING APPARATUS 5 SheetsSheet IN VENTOR.

ATTORNEY United States Patent Ofitice 3,354,964 Patented Nov. 28, 1967 WELL BORE PAC-KING APPARATUS David E. Young, Bellaire, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation ofTexas H q 7 Filed Dec. 10, 1965, Ser. No. 512,858 Claims. (Cl. 166-120) This invention relates to apparatus for packing off a well bore; and, more particularly, to packing apparatus which, when set in place, will be anchored and sealingly engaged in the well against pressure 'dilferentials acting from either direction on the apparatus by forces proportionately related to the acting pressure differentials.

In conducting such well completion operations as acidizing, cementing, or fracturing, full-opening well packer dependently coupled from a tubing string is positioned at a particular depth in a cased well and the packer set to isolate the formation interval to be treated from the remainder of the well bore thereabove. Treating fluids are then pumped downwardly at high pressure through the tubing and packer and introduced into the formation being treated through perforations appropriately located in the casing.

In those instances where a well having several producing formations is being completed, a selectively operable bridge plug is usually dependently coupled beneath the full-opening packer. Such a bridge plug permits intervals of selected length to be packed-oft for selective treatment of different formation zones with only a single trip into the well. It will be appreciated that during the course of such completion operations, these packing apparatus are usually subjected to high fluid pressures acting alternately from both above and below them. Thus, these packers and bridge plugs must be firmly sealed and securely anchored against pressure differentials acting in either longitudinal direction.

Accordingly, it is an object of the present invention to provide new and improved packing apparatus having hydraulically actuated packing means and wall-engaging anchoring members which are respectively maintained in sealing and anchoring engagement by forces proportionately related to pressure differentials between fluids in the well above and below the apparatus.

Packing apparatus arranged in accordance with the invention includes hydraulic means that are selectively operable for initially setting the packing element and anchoring the apparatus in the well bore with predetermined engaging forces and, thereafter, respond to pressure differentials across the packing apparatus to maintain the packing element and wall-engaging means in engagement with forces that are proportionately related to these differentials.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view of a full bore packer and a bridge plug of the present invention and depicted as they would appear within a well bore;

FIGS. 2A-2D are successive, detailed cross-sectional views of one embodiment of a bridge plug having hydraulically actuated packing means and anchoring means in accordance with the present invention;

FIG. 3 is a cross-sectional view taken along the lines 33 of FIGS. 2B and 8B;

FIGS. 4A4C are successive views similar to FIGS. 2B-2D but depicting the bridge plug as it will appear when set Within a well bore;

FIG. 5 is an enlarged view of the control means of the present invention;

FIGS. 6 and 7 are cross-sectional views taken respectively along the lines 66 and 77 in FIG. 5; and

FIGS. 8A-8C are views of an alternate embodiment of a bridge plug employing the principles of the present invention.

In general, the retrievable bridge plug 10 of the present invention is comprised of an actuating mandrel 11 that is 'telescoped within a tubular housing 12 and selectively movable therein between an intermediate neutral position (FIG. 2 and an operative position (FIG. 4) in which the mandrel is free to shift a limited distance either upwardly or downwardly relative to the housing. Pressure-developing means 13 are included which, as the mandrel 11 shifts relative to the housing 12, will develop sufiicient pressure to extend pressure-responsive packing means 14 and anchoring means 15 outwardly into firm engagement with an adjacent wall in a well bore. Control means 16, including valve means 17 which are selectively operated by movement of the mandrel 11 into and out of an operative position, are provided to regulate the hydraulic pressure applied to the packing means 14 and anchoring means 15 to insure that they remain firmly engaged irrespective of further shifting of the mandrel until it is returned to its neutral position. Other pressure-developing means 18 are employed to develop a sufiicient initial pressure to urge the anchoring means 15 against the well bore wall with sufiicient force to secure the housing 12 for moving of the mandrel 11 relative thereto.

Since those skilled in the art will recognize that such a well tool is typically comprised of separate tubular elements threadedly connected to one another to facilitate its manufacture and assembly, the drawings have been somewhat simplified by showing some of these separate elements as a single member for purposes of greater clarity.

Turning now to FIG. 1, a typical full-bore packer 19 is dependently connected to a tubing string 20 and positioned within a well bore 21 having a casing 22 set therein. A retrievable bridge plug 10 arranged in accordance with the present invention is releasably coupled by a fishing neck 23 to an overshot 24 dependently connected beneath the packer 19.

Matched J-slots 25 (FIG. 2A) are arranged on opposite sides of the fishing neck 23 to cooperatively receive inwardly projecting lugs 26 on the overshot 24 whenever it is lowered over the fishing neck. After the lugs 26 have entered the open upper end of the long portion of the J-slots 25, the lugs are lockingly engaged in the closed short portion of the J-slots by a concerted application of counter-clockwise torque and a slight upward pull on the tubing string 20. Conversely, the overshot 24 is selectively disengaged from the fishing neck 23 by lowering the tubing string 20 slightly, torquing it to the right, and then pulling upwardly. By employing such a releasable coupling, the bridge plug 10 can be set at the lower limit of a particular formation interval and the packer 19 uncoupled and subsequently set thereabove irrespective of the length of the tubing sub 27 connecting them.

Fluid communication through the mandrel bore 28 is selectively controlled by an annular valve member 29 which is slidably disposed around the mandrel 11 immediately around lateral bypass ports 30 therein and fluidly sealed thereto by O-rings 31 and 32 straddling the bypass ports. Lateral ports 33 are appropriately arranged in the slidable valve member 29 to register with the bypass ports 30 whenever the valve member is in 3 the position illustrated in FIG. 2. The slidable valve member 29 is arranged to be shifted longitudinally by the overshot 24 so that the ports 30 and 33 are brought into register as the overshot is being engaged over the fishing neck 23 (FIG. 2A) and the bypass ports are covered by the valve member whenever the overshot is removed.

Whenever the overshot 24 is being removed, a group of dependent resilient fingers 34 spaced around the lower portion of the overshot have inwardly projecting shoulders 35 that engage a shoulder 36 on the sliding valve member 29 to pull it upwardly and close the bypass ports 30. As the valve member 2") is pulled upwardly, depending resilient fingers 37 around the lower end of the valve member are cammed outwardly as they pass over an annular shoulder 38 around the mandrel 11. After clearing the mandrel shoulder 38, the lower ends of these fingers 37 then engage the annular shoulder to hold the slidable valve member 29 in its uppermost or port-closed position (not shown) after the overshot 24 has been removed. A shoulder 39 projecting inwardly from the central portion of the overshot 24 engages the valve member 29 and shifts it downwardly to its open position (FIG. 2A) whenever the overshot is coupled to the fishing neck 23.

As seen in FIG. 2B, the pressure-responsive packing means 14 include a slidable sleeve member 40 having an outwardly enlarged upped end 41 and an outwardly enlarged lower end 42 that is telescopically fitted within the upper portion of the tubular housing 12 and fluidly-sealed thereto by an O-ring 43 below an inwardly projecting housing shoulder 44. A shorter slidable sleeve member 45 is telescopically arranged around the central portion of the other setting sleeve 40 and has a lower end 46 extending into the housing 12 above the housing shoulder 44 and a projecting, outwardly enlarged upper end 47 that is shouldered on the upper housing end 48 and fluidly sealed to the inner sleeve by an O-ring 49. An O-ring 50 in the upper housing end 48 fluidly seals the shorter outer setting sleeve 45 to the housing 12 and defines an enclosed space 51 between the setting sleeves 40 and 45 and the other O-rings 45 and 49. An elongated external spline 52 extending longitudinally along the inner setting sleeve 40 is cooperatively received within complementary internal grooves 53 and 54 in the housing shoulder 44 and shorter outer sleeve 45 to co-rotatively secure the three members to one another and limit their relative movement to longitudinal telescopic travel.

Elastomeric packing means 14, such as a plurality of stacked annular elements 55 mounted around the exposed portion of the inner sleeve, are arranged between the outwardly enlarged upper ends 41 and 47 of the sleeves 40 and 45 to be foreshortened thereby and expanded outwardly whenever the setting sleeves arerelatively telescoped together. Conversely, longitudinal movement in the opposite direction of the sleeve ends 41 and 47 as the setting sleeves 40 and 45 expand allow the packing rings 55 to relax and return to their normal position. Thus, it will be appreciated that, upon application of sufiicient hydraulic pressure in the enclosed space 51, the setting sleeves 40 and 45 will be telescoped. As the setting sleeves 40 and 45 contract, the elastomeric elements 55 will be foreshortened and expanded radially outwardly against the casing wall. By oppropriately selecting elements 55 having a particular elasticity and dimensions suitable for a given range of casing diameters, it can be readily determined that, for a given hydraulic pressure in the enclosed space 51, the elements will be urged against the casing 22 with a force proportionately related to this hydraulic pressure. Accordingly, those skilled in the art will understand that by applying at least a predetermined hydraulic pressure in the enclosed space 51, the elastomeric elements 55 will be sealingly engaged against the casing 22 with a force sufficient to withstand well bore pressure differentials up to a particular magnitude.

Mounted around the central portion of the housing 12 is the hydraulically actuated, radially expansible anchor 15 (FIGS. 2B-2C), with parts thereof as also shown in cross-section in FIG. 3. This anchor 15 includes an expansible elastomeric sleeve 56 encircling the central portion of the housing 12 with a plurality of elongated wallengaging members 57 and 58 being longitudinally mounted uniformly around the periphery of the sleeve. The enlarged upper and lower ends 59 and 60 of the elastomeric sleeve 56 are secured by slidable annular retainers 61 and 62 within opposed peripheral recesses 63 and 64 around the housing 12. O-rings 65 and 66 around the retainers 61 and 62 fluidly seal the sleeve ends 59 and 60 within the recesses 63 and 64 to provide a fluid-tight space 67 between the sleeve 56 and housing 12.

Each of the casing-engaging members 57 and 58 is elongated and has a thick, arcuate cross-section( FIG. 3). Alternate ones of the casing-engaging members are centrally aligned and mounted on the outer convex surface of relatively thin, elongated, arcuate backing members 68. A suflicient number of these mounted members 57 are disposed around the periphery of the elastomeric sleeve 56 that the backing members 68 substantially encompass the sleeve. The remaining casing-engagingmembers 58 are unmounted and alternately disposed between the mounted casing-engaging members 57 in such a manner that the unmounted members 58 straddle adjacent backing members 68 and cover the gaps 69 therebetween.

The ends of the casing-engaging members 57 and 58 are beveled, as at 70 (FIG. 2C), for reception within the opposed annular housing recesses 63 and 64. It will be appreciated that, although the casing-engaging members 57 and 53 will move radially outwardly whenever the elastomeric sleeve 56 is inflated, the beveled ends of the members cannot escape from the housing recesses 63 and 64.

By applying hydraulic pressure within the fluid-tight space 67, the casing-engaging members 57 and 58 will be urged against the casing with a force proportionately related to this pressure. Thus, by appropriately selecting the materials and contact surface areas for causing-engaging members 57 and 53, it can be readily determined that a particular hydraulic pressure in the fluid-tight space 67 will secure the bridge plug 10 against longitudinal shifting by pressure diiferentials in the well up to a particular magnitude.

The actuating mandrel 11 is movably disposed through the inner setting sleeve 40 and extends on downwardly into the housing 12. O-rings 71 and 72 at each end of the mandrel 11 respectively fiuidly seal the mandrel to the inner sleeve 40 and lower end of the housing 12. To establish the longitudinal position of the mandrel 11 relative to the housing 12, an outwardly projecting lug 73 on the mandrel is confined within an inwardly directed T-shaped slot 74 formed in the inner wall of the housing. As shown in FIG. 2B, the T-slot 74 has an elongated portion 75 extending longitudinally along the housing 12 and a shorter longitudinal portion 76 spaced apart therefrom and connected thereto by a transverse portion 77 extending between the centers of the longitudinal slot portions.

As will be seen from FIG. 2, so long as the mandrel lug 73 is confined in the shorter slot portion 76, the mandrel 11 is substantially restrained from moving longitudinally relative to the housing 12. However, by rotating the mandrel 11 in a clockwise direction to bring the lug 73 through the transverse slot portion 77 into the elongated slot portion 75, the mandrel is then free to shift longitudinally relative to the housing 12 a distance determined by the length of the elongated slot portion.

Turning now to the pressure-developing means 13 for the bridge plug 10, the housing 12 is formed in such a manner as to provide an annular chamber 78 (FIG. 28) above the upper end of the anchor 15. A similar annular chamber 79 (FIG. 2C) is also formed below the lower end of the anchor 15. An annular clearance space 80 between the mandrel 11 and housing 12 provides fluid communication from the upper chamber 78 to the lower chamber 79. A longitudinal passage 81 through the housing 12 provides fluid communication from the fluid-tight space 67 under the elastomeric sleeve 56 to the enclosed space 51 between the setting sleeves 40 and 45. Similarly, another passage 82 through the housing 12 provides fluid communication from the fluid-tight space 67 to a valve chamber 83 below the elastomeric sleeve 56. Thus, the passages 81 and 82 interconnect the enclosed space 51 and fluid-tight space 67 to the valve chamber 83. Filling ports with closure members (not all shown) are provided at appropriate locations for introducing a suitable hydraulic fluid into the hydraulic system.

The upper end of the upper annular chamber 78 and the 'lower end of the lower annular chamber 79 are respectively closed by annular piston members 84 and 85 which are slidably mounted relative to both the housing 12 and mandrel 11. The upper slidable piston member 84 (FIG. 2B) is adapted to engage a downwardly directed shoulder 86 formed in the housing 12 at the upper end of the upper chamber 78. Annular grooves around the outer and inner surfaces, respectively, of the upper piston member receive O-rings 87 and 88 which fluidly seal the slidable piston member 84 relative to the housing 12 as well as to the mandrel 11.

The lower slidable piston member 85 (FIG. 2C) is biased downwardly by a spring 89 so that the lower piston member normally rests against an upwardly directed shoulder 90 formed in the housing 12 at the lower end of the lower chamber 79. Similarly, external and internal annular grooves around the piston member 85 receive O-rings 91 and 92 to fluidly seal the slidable piston member relative to 'both the housing 12 and the mandrel 11.

A shoulder 93 (FIG. 2B) located on the mandrel 11 a short distance above the upper slidable piston 84 is so arranged that whenever the mandrel shifts downwardly, the shoulder will engage the upper piston and force it downwardly. Similarly, a second shoulder 94 (FIG. 2C) is provided on the mandrel 11 to engage and shift the lower piston member 85 upwardly whenever the mandrel shifts in that direction. It will be appreciated, therefore, that with a suitable fluid in the above-described hydraulic system, longitudinal shifting of the mandrel 11 in either direction will develop a uniform pressure throughout the system that is related to the distance that the mandrel shifts. Thus, as previously described, this developed hydraulic pressure is employed to telescope the setting sleeves 40 and 45 for expanding the packing elements 55 and to press the casing-engaging members 57 and 58 against the casing 22.

The other pressure-developing means 18 include an annular compensating chamber 95 (FIGS. 2C-2D) that is formed in the housing 12 beneath the lower piston member 85 to maintain a supply of fluid in the hydraulic system as well as to compensate for thermal expansion of the hydraulic fluid. The lower end of this annular chamber 95 is closed by a slidable annular compensating piston member 96 having 'O-rings 97 and 98 around its outer and inner surfaces which fluidly seal the compensating piston relative to the housing 12. Means, such as a spring 99 engaged between the compensating piston 96 and an upwardly facing housing shoulder 100, are provided to accommodate thermal expansion of the hydraulic fluid as well as to bias the compensating piston against the hydraulic fluid.

Selectively controlled fluid communication is provided between the compensating chamber 95 and the remainder ofthe hydraulic system through a housing passage 101 and an annular clearance space for-med by a reduceddiameter portion 102 around the mandrel 11. This reduced-diameter portion 102 is arranged to be normally in juxaposition with the lower piston 85 whenever the mandrel 11 is in its intermediate neutral position as determined by the mandrel lug 73 being confined within 6 the shorter slot 74. When, however, the mandrel 11 has been so manipulated to shift the lug 73 into the longer slot 75 and the mandrel is shifted longitudinally only a slight distance in either direction, the inner O-ring 92 within the lower piston member fluidly seals the piston to the mandrel at either 103 or 104 depending upon the direction in which the mandrel has been shifted.

Accordingly, it will be seen that so long as the mandrel 11 is in a neutral or intermediate position (as determined by the lug 73 being within the short slot 76), the mandrel is substantially restrained from shifting longitudinally in either direction and the upper and lower piston members 84 and 85 will be substantially in the positions illustrated in FIG. 2 with the mandrel shoulders 93 and 94 separated therefrom. When the mandrel 11 is in the above-mentioned intermediate position, the reduced-diameter mandrel portion 102 will permit free communication of hydraulic fluid from the compensating chamber into the remainder of the hydraulic system above the lower piston 85. This communication will allow the fluid in the hydraulic system to expand as its temperature increases during a descent into a well here. It will be recognized, of course, that when hydraulic pressure is to be developed in the system by shifting either piston 84 or piston 85, it is best to close the communication through portion 102 to the compensating chamber 95. Thus, by closing communication to the compensating chamber 95 as the mandrel 11 is first shifted, less travel of the mandrel is required to develop an effective hydraulic pressure.

When the bridge plug 10 is being set, it will be apparent that as the mandrel lug 73 is being shifted within its T-slot 74, means must be provided to hold the housing 12 fixed relative to the mandrel 11. Moreover, after the bridge plug 10 has been set, the housing 12 must remain anchored to the casing 22 with at least a minimum holding force whenever the mandrel 11 is not sufliciently displaced to coact with one of the pistons 84 and 85 or is shifting through its intermediate position to one of its other positions. Although conventional spring-biased drag blocks could be successfully employed for this purpose, it is preferred to instead select a spring or springs, as at 99, that have an effective spring rate to bias the compensating piston 96 with suflicient force to develop a slight hydraulic pressure in the hydraulic system.

By developing a predetermined hydraulic pressure in the system in this manner, the casing-engaging members 57 and 58 will be urged against the casing 22 with suflicient holding force to permit movement of the mandrel 11 relative to the housing 12 but without unduly limiting the positioning of the bridge plug 10. Moreover, once the casing-engaging members 57 and 58 are extended against the casing 22, it will be appreciated that subsequent shifting of the mandrel 11 will be immediately effective to develop additional hydraulic pressure since the elastomeric sleeve 56 will already be inflated.

It will, of course, be recognized that since the well bore pressure is acting against both the compensating piston 96 and elastomeric sleeve 56, the pressure in the hydraulic system will be equal to the sum of the Well bore pressure plus the pressure developed by the spring 99. Thus, the spring rate of the spring 99 will directly determine the force with which the casing-engaging members 57 and 58 are urged against the casing 22. It will be further understood that the pressure developed in the hydraulic system by the action of the spring 99 against the compensating piston 96 is not suifiicent to significantly foreshorten the packing elements 55. Accordingly, as the bridge plug 10 is being moved into position within the Well bore 21, the anchoring means 15 will serve as drag blocks but the packing means 14 will remain substantially retracted.

When the bridge plug 10 is to be set in a well, the mandrel 11 is appropriately manipulated by the tubing string 20 to shift the mandrel lug 73 into the elongated slot portion 75 of the T-slot 74. Once the mandrel lug 73 is in the longer slot portion 75, the mandrel 11 is free to shift either upwardly or downwadrly to engage either the lower piston 85 or upper piston 84 and develop a hydraulic pressure in the system for actuating the pressureresponsive anchor means 15 and packing means 14. Thus, once the mandrel 11 is lowered or elevated, the bridge plug will be firmly anchored and sealingly packedoit.

It will be appreciated, however, that unless the mandrel 11 remains in one of its displaced positions, the developed hydraulic pressure will vary as the mandrel shifts relative to the housing 12. Thus, for example, after the overshot 24 is released from the fishing neck 23, the mandrel 11 will assume a position (within the limits established by the length of the slot portion 75) that will be dictated by the magnitude and direction of whatever, if any, pressure differential there may be across the bridge plug 10. Thus, with a low pressure ditferential, there will be a proportionately low pressure developed in the hydraulic system.

Although the effective holding force to be applied by the anchor means need not be any greater than that developed by the shifting of the mandrel 11 in response to any given pressure diiterential, it will be realized that to maintain an effective seal with the packing elements 55 they must be held firmly engaged against the casing 22. Accordingly, the bridge plug 10 includes control means 16 for selectively regulating the hydraulic pressure being applied to the pressure-responsive means 14 and 15 whereby the applied pressure will be maintained even though the developed pressure decreases but will still be increased upon further increases of the developed pressure. Moreover, it will be recognized that until the pressure-developing means 13 have been actuated to set the packing means 14- and firmly engage the anchoring means 15, the control means 16 must communicate the slight pressure developed in the compensating chamber 05 to the anchoring means to secure the housing 12 for movement of the mandrel 11 relative thereto.

To accomplish these purposes, an annular valve body 105 is disposed in the valve chamber 83 below the anchoring means 15 and fluidly sealed therein to the housing 12 by O-rings 106 and 107. In this manner, the valve chamber 83 is divided into an outer sealed space 108 and an inner sealed space 109. The outer sealed space 108 is connected to the anchoring means 15 by the housing passage 82 and also to the enclosed space 51 between the setting sleeve 40 and 45 by way of the fluid-tight space 67 under the elastomeric sleeve 56 and the housing passage 81. As shown, this inner sealed space 109 within the valve body 105 may be a continuation of the annular clearance 80 communicating the upper and lower chambers 78 and 79 of the pressure-developing means 13. Thus, it will be appreicated that the valve body 105 isolates the pressure-responsive means 14 and 15 from the pressure-developing means 13.

Accordingly, to provide selective fluid communication from the pressure-developing means 13 to the pressureresponsive means 14 and 15, a conventional spring-biased unidirectional check valve 110 is disposed in a longitudinal passage 111 through one side of the valve body 105 between the inner and outer sealed spaces 108 and 109. By selecting a check valve 110 that will open under a slight pressure differential and appropriately arranging it in the passage 111, substantially unrestricted fluid communication is provided from the pressure-developing means 13 to the pressure-responsive means 14 and 15. On the other hand, the check valve 110 will prevent fluid communication from the pressure-responsive means 14 and 15 back to the pressure-developing means 13. Thus, before the bridge plug 10 is set, Whatever hydraulic pressure that is developed by the compensating piston 96 will be readily transmitted from the compensating cham- ,1 c1 ber 95 to the anchoring means 15 by way of the check valve 110 and its associated fluid passage 111.

As previously mentioned, when the bridge plug 10 is to be set, the mandrel 11 is rotated to shift the lug 73 from the shorter slot portion 76 to the longer portion of the T-slot 74. Once the mandrel lug 73 is in the longer slot portion 75, the mandrel 11 is then shifted (by the tubing string 20) in either longitudinal direction relative to the housing 12 to develop a substantial hydraulic pressure sufi'icient for expanding the elastomeric packing elements 55 outwardly into sealing engagement with the casing 22 and firmly engaging the anchoring means 15. This increased hydraulic pressure is, of course, readily transmitted through the check valve 110.

Once, however, such an increased hydraulic pressure is applied in the enclosed spaces 51 and 67 between the setting sleeves 40 and 45 and under the elastomeric sleeve 56, the check valve 110 will prevent loss of this pressure through the passage 111 regardless of any subsequent decrease in developed hydraulic pressure as will occur, for example, when the mandrel 11 approaches the center of its span of travel. It should also be noted that should the pressure-developing means 13 subsequently develop a higher hydraulic pressure than that already trapped within the enclosed spaces 51 and 67, the check valve 110 will, of course, re-open to admit this higher pressure into these enclosed spaces.

It will be appreciated, however, that to retrieve the bridge plug 10, the hydraulic pressure in the fluid-tight spaces 67 and 51 beneath the elastomeric sleeve 56 and between the setting sleeves 40 and 45 must be relieved to retract the pressure-responsive means 14 and 15. Moreover, as the bridge plug 10 is being positioned in a well bore, it will be recalled that the casing-engaging members 57 and 58 will be maintained against the casing 22 by the operation of the compensating piston 96.

Thus, should the bridge plug 10 move from one joint of casing 22 to another of slightly larger diameter, the spring 99 will shift the compensating piston as upwardly enough to keep the casing-engaging members 57 and 58 against the casing. It further movement of the bridge plug 10 carries it into yet another joint of casing 22 of a smaller diameter, the casing-engaging members 57 and 58 must retract slightly to accommodate the smaller diameter and this retraction will increase the pressure in the hydraulic system unless the fluid in the fluid-tight space 67 can return freely to the compensating chamber 95. It will be recognized that the check vaive 110 will not permit such return communication through the passage 111.

Accordingly, the control means 16 of the present invention includes valve means 17 that are selectively operable between one condition of operation to permit substantially unrestricted return fiuid communication from the pressure-responsive means 14 and 15 back to the compensating chamber and another condition of operation where such return communication is regulated. To accomplish such selective operation, actuating means 112 are provided which respond to movement of the mandrel 11 as the lug 73 is shifted from the shorter slot portion 76 to the longer slot portion '75.

As best seen in FIG. 5, the valve means 17 includes a slidable actuator 113 that is disposed in a longitudinal bore 114 through the valve body and arranged to slide therein between spaced longitudinal positions as shown in FIGS. 2 and 4. An annular valve seat 115 is fluidly sealed in the longitudinal bore 114 and adapted to receive a movable valve member, such as a ball 116, in the bore therebelow between the valve seat and actuator 113. To maintain the ball 116 in operative relation to the valve seat 115, a conventional cage 117 is disposed in the bore 114 to loosely retain the ball in alignment with the actuator 113.

The upper portion of the actuator 113 is coaxially counterbored, as at 118, to partially receive a compression spring 119 that projects upwardly a short distance there- Q above. A retainer, such as a removable screw 120, is coaxially mounted in the actuator bore 118 and extended through the spring 119. To maintain the spring 119 in compression, a washer 121 is loosely fitted around the screw shank below the screw head and engaged on the top of the spring. Thus, by suitably selecting the various dimensions of the related elements, the spring 119 will normally be held in compression between the bottom of the bore 118 and the underside of the washer 121. By threading or unthreading the screw 120, the force applied against the washer 121 may be varied to suit a particular operating condition as will subsequently become apparent.

A slidable follower 122 having a coaxially aligned upright extension 123 and a hollowed, downwardly extending skirt 124 is slidably disposed in the longitudinal bore 114 below the ball 116. The follower extension 123 is adapted to pass into the ball cage 117 and engage the ball 116. The follower skirt 124 is suitably proportioned to rest on the exposed portion of the washer 121 extending beyond the head of the screw 120 so that the screw head can pass into the hollowed skirt without engaging the follower 122.

A transverse passage 125 through the body 105 provides fluid communication between a longitudinal bore 126 above the seat 115 and the outer sealed space 108 around the valve body. Likewise, to facilitate fluid communication through the longitudinal bore 114 between the inner sealed space 109 and valve seat 115, bypass means, such as longitudinal flutes 127 and 128 (FIGS. 6 and 7) formed around the actuator 113 and follower 124, are provided.

To actuate the valve means 17, a flat transverse cam surface 129 is formed along a chord across the mandrel 11 adjacent to the valve body 105 and a cam, such as a ball 13%, is loosely fitted in an opening 131 through the valve body adjacent to the flat surface. An annular member 132 below the valve body 105 retains the ball 139 in position. The lower end of the actuator 113 is skewed to provide a beveled transverse cam surface 133 that is tangentially engaged by the ball 130. By aligning the cam surfaces 129 and 133 along intersecting transverse planes, when the ball 130 is shifted radially outwardly by rotation of the mandrel 11, the actuator 113 is shifted longitudinally upwardly. To maintain the skewed surface 133 against the ball 130 and in proper orientation to the mandrel surface 129, a radial pin 134 in the actuator 113 is loosely fitted within a longitudinal slot 135 along one surface of the longitudinal bore 114.

By aligning the mandrel fiat 129 and actuator skewed surface 133 in proper relation to the mandrel lug 73 and T=slot 74, it will be appreciated that when the mandrel lug is in the shorter slot portion 76, the ball 130 will be displaced inwardly and resting on the mandrel flat to allow the actuator 113 to assume its lowered position as shown in FIG. 2. Conversely, as the mandrel lug 73 is shifted into the longer slot portion 75, the mandrel flat 129 will be rotated from under the ball 130 and the ball will be cammed radially outwardly as the full-diameter mandrel surface, as at 136 (FIGS. and 7), is rotated under the ball. Thus, it will be recognized by comparison of FIGS. 2 and 4 that in this latter mandrel position, the outward camming of the ball 130 against the skewed cam surface 133 will in turn shift the actuator 113 longitudinally upwardly.

Accordingly, by appropriately arranging the pertinent dimensions of the various elements of the valve means 17, the follower extension 123 will engage the check ball 116 and urge it against the valve seat 115. As the ball 116 is urged against its seat 115, the follower skirt 124 will shift the washer 121 downwardly against the force of the spring 119 and away from the underside of the head of the screw 120. Thus, the full force of the spring 119 will be urging the check ball 116 into seating engagement with the valve seat 115. It will be recognized, of course, that this will require a pressure differential tending to 10 open the check ball 116 to reach a particular magnitude commensurate with the spring force before the check ball will be unseated.

It will be understood, however, that although the spring 119 need not be normally held in compression by the engagement of the washer 121 against the head of the screw 120, it is preferred to pre-load the spring to insure that a spring force of at least a predetermined magnitude is imposed against the check ball 116 when it is seated. By compensating for manufacturing tolerance in this manner, the force required to unseat the check ball 116 will be whatever preloaded force is given to the spring 119 plus whatever slight additional spring force is developed whenever the spring is further compressed as the check ball is unseated.

Thus, it will be seen that the control means 16 serves to regulate the hydraulic pressure applied to the pressureresponsive means 14 and 15. When the bridge plug 10 is in its retracted position (FIG. 2), the pressure-developing means 13 is deactivated and only whatever hydraulic pressure is developed by the compensating pressure-developing means 18 will be admitted through the reduceddiameter mandrel portion 102 and check valve (and quite possibly the ball valve 116) to the pressure-responsive means 14 and 15. In this situation, as already discussed, the compensating spring 99 and piston 96 are capable of developing a hydraulic pressure suflicient only to urge the casing-engaging members 57 and 58 outwardly with a moderate holding force. This moderate holding force will suflice to secure the housing 12 to the casing 22 to permit the movement of the mandrel 11 relative thereto. Any increase of hydraulic pressure in the space 67 under the elastomeric sleeve 56 (as developed by inward movement of the casing-engaging members 57 and 58) will be relieved through the valve seat and around the ball valve 116 to the compensating chamber 95.

Then, whenever the mandrel 11 is rotated to shift the mandrel lug 73 into the elongated slot portion 75, the follower ball will be cammed outwardly to urge the actuator 113 upwardly to urge the ball valve 116 against its seat 115. With the fluid communication closed through the valve seat 115, only the check valve 110 will open as the mandrel 11 shifts to actuate the pressure-developing means 13. Since the check valve 110 will function only to admit a higher developed hydraulic pressure to the pressure-responsive means 14 and 15, the packing elements 55 and casing-engaging members 57 and 58 will be extended against the casing 22 with a force proportional to the pressure developed by the pressure-developing means 13. Accordingly, the pressure-responsive means 14 and 15 will be firmly engaged against the casing 22 as the bridge plug 10 is set.

After the bridge plug 10 is set, it will be recognized that the hydraulic pressure applied to the pressureresponsive means 14 and 15 will always be maintained at a high magnitude. Should the hydraulic pressure within the pressure-developing means 13 decrease sufficiently, the ball valve 116 will open to relieve the pressure applied to the pressure-responsive means 14 and 15 to some predetermined magnitude greater than that in the pressure-developing means as determined by the force applied by the spring 119. Then, the ball valve 116 will again close. Any increase of developed pressure, however, will be admitted through the check valve 110 to the pressureresponsive means 14 and 15.

When the bridge plug 10 is to be retrieved, it is necessary only to return the mandrel lug 73 to the shorter slot portion 76. As the mandrel 11 is rotated, the follower ball 130 is again re-engaged on the mandrel flat 129 to allow the actuator 113 to return to its lower position. As the actuator 113 returns, the valve means 17 will open to again equalize the pressure in the hydraulic system. Thus, the pressure-responsive means 14 and 15 will retract and the bridge plug 10 can be retrieved.

It is also of special significance to the present invention that the packing means 14 are settable without further hydraulic pressure being developed by action of the pressure differential in the well bore on the packing elements 55 or setting sleeves 4t} and 45 themselves. For example, assume that there was no outer setting sleeve 45 on the present bridge plug 19 and the lower packing elements 55 merely rested on top of the upper housing end 48. In such an instance, a well bore pressure differential acting upwardly across the bridge plug would tend to build up hydraulic pressure within the enclosed space 51. Such a pressure would be trapped in this space 51 and, if it were not for the valve teams 17, could quite possibly develop a hydraulic pressure sufficient to burst the housing 12 or cause failure of an O-ring, as at 43, for example. Other conventional setting sleeves are similarly susceptible to such hazards.

The present invention avoids such hazards, however, by arranging the setting sleeves 40 and 45 to telescope Within one another and to be separated by a rigid stop as provided by the housing shoulder 44. It will be recognized that this unique arrangement prevents such a hazard from arising. Thus, should there be an increased pressure differential from above the set bridge plug 10, the inner setting sleeve 40 will be depressed and further foreshorten the packing elements 55. This downward shifting of the setting sleeve 40, however, will not cause an increase in the hydraulic pressure in the enclosed space 51 since movement of the lower piston end 42 of the setting sleeve will increase the volume of the enclosed space. The downward travel of the mandrel 11 in response to this increased pressure differential will shift the upper piston 84 sufficiently to develop an increased hydraulic pressure in the enclosed space 51 that is proportionately related to the differential. The outer setting sleeve 45 cannot shift downwardly since it will be stopped by the upper housing end 48. It will be noted that an increased pressure differential from below the set bridge plug 16 will have a similar action on the outer setting sleeve 45, with the housing shoulder 44 serving as a stop for the inner setting sleeve 4Q.

When the bridge plug 10 has been positioned at the depth at which it is to be set, it is halted and an upward strain is taken on the tubing string 26 as it is rotated to the right. This concerted application of tension with clockwise torque will bring the mandrel lug 7.3 into alignment with and then shift it through the transverse slot portion 77 into the elongated slot portion '75 of the T-slot 74.

Once the mandrel lug 73 is shifted into the elongated slot portion 75, the mandrel 11 is free to be shifted the full limit permitted by the slot portion 75. Accordingly, by shifting the tubing string 20 either upwardly or downwardly, the pressure-developing means 13 will be employed as already described to develop a sufficient hydraulic pressure for setting the bridge plug 10.

Then, as the hydraulic pressure is increased, the elastomeric packing elements 55 will be foreshortened by the setting sleeves 40 and 45 and thereby expanded into sealing engagement with the casing 22. Similarly, as the hydraulic pressure is developed, the casing-engaging members 57 and 58 will be urged against the casing 22 to anchor the bridge plug 10 securely. Once the packing means 14 and anchoring means 15 are engaged, the overshot 24 is removed from the fishing neck 23. As the overshot 24 is removed, the valve member 29 is pulled upwardly thereby to close the bypass ports 30 and the central bore 28 through the mandrel 11.

It will be recognized, of course, that after the overshot 24 has been disengaged from the fishing neck 23, the mandrel 11 is free to shift longitudinally within the limits determined by the length of the longitudinal housing slot 75. Any pressure differential across the packing elements 55 will also act on the mandrel 11. Should the pressure in the well bore 21 above the bridge plug 10 be greater than the pressure below, the pressure differential will act to shift the mandrel 11 downwardly. Downward shifting of the mandrel 11 will cause the shoulder 93 to drive the upper slidable piston member 84 downwardly, which action will result in increasing the hydraulic pressure within the system to press the casing-engaging members 57 and 58 of the anchor 15 against the well casing 22 with a force proportionately related to the pressure differential across the bridge plug 10.

Should, perchance, the pressure in the well bore 21 below the bridge plug 10 become greater than the pressure thereabove, the mandrel 11 Will be shifted upwardly. As the mandrel 11 shifts upwardly, the hydraulic pressure will be momentarily reduced as the upper piston member 84 returns to its initial position against housing shoulder 86. Moreover, as the reduced-diameter mandrel portion 102 passes upwardly relative to O-ring 92 within the lower piston 85, there will be a momentary resumption of fluid communication between the hydraulic system and the compensating chamber 95. At this point, however, the check valve 110 and valve means 17 will maintain the pressure within that portion of the hydraulic system thereabove at a sufficient magnitude to keep the packing elements 55 and wall-engaging members 57 and 58 firmly secured against the casing 22. Then, as the mandrel 11 continues to travel upwardly, the reduced-diameter mandrel portion 102 will move upwardly relative to the lower piston which will then itself be shifted upwardly by the lower mandrel shoulder 94. Should the mandrel 11 continue its upward movement a sufficient distance, hydraulic pressure will again be increased within the fluidfilled hydraulic system to again urge the packing elements 55 and casing-engaging members 57 and 58 against the casing 22 with a greater force that is proportionately related to the pressure differential across the bridge plug 10.

It must be emphasized, however, that regardless of the shifting of the mandrel 11, the ball valve 116 will remain in the position shown in FIG. 5 and the check valve 110 will function to trap whatever pressure is needed to maintain the casing-engaging members 57 and 58 and packing elements 55 firmly engaged with the casing 22.Thus, even as the mandrel 11 shifts to its central position, the packing means 14 will maintain sealing engagement with the casing 22. Moreover, should pressure differentials in the well require a greater sealing engagement with the casing 22, the check valve 110 will function to admit into the enclosed spaces 51 and 67 any higher hydraulic pressures developed as the mandrel 11 is shifted by such pressure differentials.

To release the bridge plug 10, it is necessary only to re-engage the overshot 24, the equalizing valve member 29 is again shifted downwardly to bring ports 33 therein into registry with mandrel ports 30. With the fluid pressure equalized across the retrievable bridge plug 10, the mandrel 11 is shifted to its intermediate position and torqued to the left to return the mandrel lug 73 through the transverse slot portion 77 into the shorter slot portion 76. I

It will be appreciated that as the mandrel lug 73 is being rotated through the slot portion 77, the valve actuator 113 will be returned downwardly (by the spring 119) to re-establish direct communication between the enclosed and fluid-tight spaces 51 and 67 and the balance of the hydraulic system. Moreover, with the mandrel 11 again in its intermediate neutral position, the compensating chamber will also again be in communication (by way of reduced mandrel portion 102) with the hydraulic system. Thus, the pressure in the system will now drop to what it was before the bridge plug 10 was set and the packing means 14 and anchoring means 15 will return to their retracted position.

It will be understood, of course, that once it is retracted and as the retrievable bridge plug 10 is being shifted, the compensating spring 99 will remain engaged with the compensating piston 96. Thus, the wall-engaging members 57 and 58 will still be held against the casing 22 with the predetermined holding force as previously described. Thus, should it be desired to position the bridge plug at a different depth without first removing it from the well bore, it is only necessary to halt the bridge plug at the desired position and repeat the above-described setting operation. Then, when it is desired to finally retrieve the bridge plug, it is necessary only to repeat the above-described retrieving operation and remove the bridge plug 10 from the well bore 21.

Turning now to FIG. 8, an alternate embodiment is shown of a bridge plug 200 incorporating the features of the present .invention. Comparison of the bridge plug 200 with the one already described will show that this alternate embodiment has pressure-responsive packing means 201 and anchoring means 202 as well as pressure developing means 203 arranged .in the same manner. Moreover, since the equalizing valve (not shown) is identical to that one (at 29) already described, it has been omitted.

The principal distinctions, therefore, between the bridge plugs 10 and 200 are that, in the latter, control means 204 are placed in the hydraulic system between the packing means 201 and anchoring means 202 and that the compensating piston 205 is releasably secured by latch means 206. As will be subsequently described in greater detail, isolation of the packing means 201 from the anchoring means 202 by the control means 204 will allow the hydraulic pressure applied to the anchoring means to vary in relation to the shifting of the mandrel 207. The control means 204 will, however, maintain the hydraulic pressure in the enclosed space 208 at a magnitude sufficient to hold the packing elements 209 sealingly engaged in the same manner as the previously described control means 17.

With the separation of the pressure-responsive means 201 and 202, it will be recognized that the casing-engaging members 210 and 211 must be urged against the casing with more residual holding force than in the bridge plug 10 of FIG. 2 since there will be situations of a slight pressure differential that could displace the bridge plug 200 without shifting the mandrel 207 sufficiently to develop a greater hydraulic pressure. Thus, in the bridge plug 200, one or more compensating springs 212 are somewhat stouter than the spring 99 so as to urge the compensating piston 205 with more force and develop a greater initial or minimum holding force.

Although this approach shown in FIG. 8 is generally successful, it has been found diflicult in some instances to shift a bridge plug 200 arranged in this manner downwardly in the well bore before it has reached a depth where the tubing string has suflicient weight to overcome the above-mentioned holding force. Inasmuch as the minimum required holding force may Well be in the order of a few thousand pounds, it will be recognized that, in some instances, several hundreds of feet of tubing will be required before the weight of the assembled tubing string will freely shift the bridge plug 200 downwardly.

Accordingly, the bridge plug 200 includes means for initially removing the spring bias from the compensating piston 205 until such time that the bridge plug has reached a substantial depth in the well bore. To accomplish this, the upper end of the springs 212 are preferably confined Within a follower sleeve 213 having an inwardly directed shoulder 214 and a depending skirt 215 to keep the individual springs concentrically positioned. A retainer sleeve 216 having an outwardly directed shoulder 217 is extended through the springs 212, with the shoulder 217 being normally disposed a short distance below the compensating piston 205 and engaged on top of the follower sleeve shoulder 214. Selectively operable latch means 206 are employed to releasably secure the retainer sleeve 216 to the housing 218 for 14 temporarily depress-ing the springs 212 away from the compensating piston 205.

In the arrangement of the latch means 206 depicted in FIG. 8C, the lower end of the retainer sleeve 216 is telescoped into the upper end of a slidable locking sleeve 219. A plurality of detents, such as balls 220 loosely mounted in the locking sleeve 219 and partially extending into a complementary annular recess 221 in the retainer sleeve 216, releasably connect the retainer sleeve to the locking sleeve. The lower end of the locking sleeve 219 is enlarged so as to define an enclosed space 222 between the sleeve end and the inwardly directed housing shoulder 223 thereabove. An O-ring 224 in the housing shoulder 223 fluidly seals the upper portion of the locking sleeve 219 to the housing 218.

At the lower end 225 of the locking sleeve, a slight clearance is left to provide a predetermined annular space 226 between the sleeve 219 and housing 218 so that a viscous fluid 227, such as grease or the like, may be confined within the enclosed space 222 therebetween. A screw 228 through the housing 218 secures the locking sleeve so that, as seen in FIG. 8, so long as the sleeve 219 is in its lowermost position, the locking balls 220 will be a short distance below an enlarged recess 229 in the inner wall of the housing shoulder 223.

It will be appreciated, therefore, that so long as the locking balls 220 remain in the retainer sleeve recess 221, the retainer sleeve 216 will remain connected to and be held down by the locking sleeve 219 and screw 228 to the housing 218 against the upwardly directed force of the springs 212. Thus, so long as the springs 212 are prevented from shifting the follower sleeve 213 against the compensating piston 205, no pressure will be developed thereby in the hydraulic system.

Accordingly, in the operation of the bridge plug 200, the screw 228 is removed a short time before the bridge plug is introduced into the casing. Once the screw 228 is removed, the springs 212 will begin urging the follower and retainer sleeves 213 and 216 upwardly. However, by appropirately selecting the viscous fluid 227 and sizing the annular clearance 226 with respect to the spring rate of springs 212, it will require a measureable time period for a sulficient volume of the fluid to be displaced through the clearance 226 and allow the locking sleeve 219 to shift upwardly where the balls 220 can enter the housing recess 229. Then, when the balls 220 enter the housing recess 229, the retainer sleeve 216 will be disconnected from the locking sleeve 219 and be free to move further upwardly with the follower sleeve 213 to engage the compensating piston 205. Once the com pensating piston 205 is biased by the springs 212, the hydraulic pressure developed thereby will be effective to frictionally engage the casing-engaging members 210 and 211 with the casing as in the bridge plug 10 previously described with respect to FIG. 2.

The control means 204 in the bridge plug 200 is similar in many respects to the control means 16 already described. It differs primarily, however, in that in the control means 204, there is free communication throughout the hydraulic system in either direction so long as the mandrel lug 230 is retained in theshorter portion 231 of the T-slot 232. Then, once the mandrel 207 is rotated to shift the lug 230 into the longer slot portion 233, the control means 204 will function to permit free communication from the pressure-developing means 203 to the packing means 201 but regulate communication in the reverse direction. With the control means 204 functioning in this latter manner, an equalizing or relief valve 234 (somewhat similar to that already described at 17) will function to relieve any excessive pressure differential between the enclosed space 208 and the pressure-developing means 203.

To accomplish this, an annular valve member 235 is slidably disposed within the housing 218 and co-rotatively secured to the mandrel 207 by a complementary longitudinal spline and groove, as at 236. Longitudinally spaced reduced-diameter portions 237 and 232 are formed around the valve member 235 to leave an intermediate full-diameter portion 239 and provide clearance between the valve member and inner wall of the housing 218. rings 24-0 and 241 above and below the reduced-diameter portions 237 and 23S fluidly seal the valve member 235 to the housing 218.

The adjacent ends of longitudinal housing passages 242 and 243 are terminated in longitudinally spaced, inwardly opening annular recesses 244 and 245 formed adjacent to one another in the internal wall of the housing 218. An O-ring 246 in the internal wall of the housing 218 between the recesses 244 and 245 is arranged to engage the intermediate full-diameter portion 239 or" the valve member 235 whenever this portion is opposite the O-ring 246.

Thus, it will be appreciated that, when the valve member 235 is so positioned that the O-ring 246 is engaged with the intermediate full-diameter portion 239 of the valve member, the reduceddiameter portions 237 and 238 will be respectively opposite the housing recesses 244 and 245 and the O-ring 246 will block direct fluid communication therebetween. Conversely, by longitudinally shifting the valve member 235 slightly downwardly with respect to the housing 218 to the position shown, the intermediate full-diameter valve member portion 239 will be displaced from sealing engagement with the O-ring 2&6 and direct fluid communication will be established between the housing recesses 244 and 245 by way of, for example, the reduced-diameter valve member portion 237. In either position of the valve member 235, the O-rings 240 and 241 at its opposite ends will straddle the housing recesses 244 and 245 and remain in sealing engagement with the inner wall of the housing 218.

It will be appreciated, therefore, that the valve member 235 will selectively open and close fluid communication through the housing passages 242 and 243 depending upon its longitudinal position relative to the housing 218. Thus, with the valve member 235 displaced slightly downwardly (as seen in FIG. 8) and its intermediate full-diameter portion 239 out of sealing engagement with the O-ring 246, there will be fluid communication from the pressuredeveloping means 203 to the enclosed space 208 between the setting sleeves 247 and 248 of the packing means 201. On the other hand, when the valve member 235 is elevated therefrom, fluid communication exterior of the valve member is blocked by the sealing engagement of O-ring 246 with the intermediate valve member portion 239.

To control this longitudinal position of the valve member 235, an inclined slot 249 is formed in the exterior of the valve member and receives an inwardly projecting housing lug 250. Accordingly, as the mandrel 207 is rotated to shift the mandrel lug 230 from the shorter slot portion 231 into the longer slot portion 233, the splined connection at 236 will rotate the valve member 235 as well. By properly arranging the inclination of the slot 249, the camming action of the housing lug 250 will shift the valve member 235 upwardly along the mandrel 207 into its elevated position. It will be recognized, of course, that the slots 232 and 249 must be so arranged relative to one another that the rotation of the mandrel 207 necessary to shift the lug 230 from one slot portion 231 to the other portion 233 will be suflicient to simultaneously elevate the valve member 235 to the desired position.

Thus, it will be understood that with the mandrel 207 in its intermediate position, there is full communication between the pressure-responsive packing means 201 and the pressure-developing means 203. With the mandrel lug 230 in the longer slot portion 233, however, this fluid communication is blocked irrespective of the longitudinal position of the mandrel 207. To provide selective control of fluid communication to and from the packing means 201, bypass means, such as a conventional springbiased unidirectional check valve 251 disposed in an interconnecting passage 252 through the valve member 235 between the reduced portions 237 and 238, are provided. Thus, with the check valve 251 correctly oriented, when the valve member 235 is cainmed upwardly into its elevated position, hydraulic fluid can move from the passage 243 to the passage 242 by way of the check valve 251 and bypass passage 252 and to the packing means 201. Flow in the reverse direction is prevented, however, by the check valve 251 as well as by the sealing engagement of the O-ring with the full-diameter valve member portion 239.

it will be recognized that means should be provided as in bridge plug 10 for limiting the magnitude of hydraulic pressure retained in the enclosed space 208 between the setting sleeves 247 and 248. To accomplish this, a check valve 253 is disposed in the valve member 235 and arranged with a sulficiently strong spring 254 to open under a predetermined hydraulic pressure differential between the enclosed space 208 and pressuredeveloping means 203. By providing a relief passage 255 between the reduced portions 237 and 238 of the valve member 235, the relief valve 253 and spring 254 will function to relieve any excessive hydraulic pressure differential between the packing means 201 and pressuredeveloping means 203. Here again, however, this relief valve 253 will not limit the application of evcn extreme hydraulic pressures to the packing means 201. It will function only to relieve such extreme pressures Whenever the hydraulic pressure in the pressure-developing means 203 decreases to the predetermined difference in pressures.

Accordingly, it will be appreciated that the present invention provides unique controls for hydraulically actuated well tools as well as for setting an expansible packing element. By providing a well tool with selectively operable control means arranged in accordance with the present invention, the tool is given substantially more flexibility in that the mandrel is movable in one manner to operate valve means; but, in another position, the mandrel is free to move without also actuating the valve means. Thus, by employing the control means of the present invention with a hydraulically actuated well packing apparatus having separately movable anchoring and packing elements, selective actuation of these elements is now possible.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A well tool sized and adapted for reception in a well bore comprising: a tubular housing; a body movably disposed within said housing and arranged for movement therein between an inactive position and an active position; pressure-responsive means movably mounted on said housing and movable relative thereto in response to a hydraulic pressure; means responsive to movement of said body toward its said active position for developing a hydraulic pressure suflicient to move said pressure-responsive means; first control means including first passage means interconnecting said pressure-developing means and pressure-responsive means and first valve means in said first passage means for admitting hydraulic pressure into said pressure-responsive means but preventing release of hydraulic pressure therefrom; and second control means including second passage means interconnecting said pressure-developing means and pressure-responsive means, second valve means in said sec ond passage means, and actuating means between said second valve means and body responsive to movement 0t said body out of said active position for closing saidsecond valve means and responsive to movement of said body into said inactive position'for opening said second valve means to release hydraulic pressure from said pressure-responsive means.

2. A well tool sizedand adapted for reception in a well .bore comprising: ..a. tubular housing; pressure-responsive packing meansincluding a .member having a .piston'por- .tiontelescopedwithin .one. end .of said housing and fluidly sealed-thereto. and an exposed portion including abutment meansspaced fromsaid'housingend, a-sleeve telescoped around an intermediate portion of said member, annular'expan'sibletpackingelement around said member and between said abutment means and sleeve,-:and means fluidly sealing said sleeve to said housing and member for defining an enclosed space between said sealing means and piston portion; a mandrel movably disposed within said housing and arranged for movement therein between spaced positions; pressure-developing means including piston means fluidly sealed within said housing and slidable in response to movement of said mandrel toward one of its said positions for developing an increased hydraulic pressure; and passage means interconnecting said pressure-developing means and said enclosed space.

3. A well tool sized and adapted for reception in a well bore comprising: a tubular housing; a mandrel telescopically disposed within said housing and arranged for movement therein from an inactive position to longitudinallyspaced active positions; pressure-responsive packing means on said housing and movable relative thereto from a retracted position to an extended position upon application of hydraulic pressure thereto; means including piston means fluidly sealed within said housing and slidable in response to movement of said mandrel toward a first one of its said active positions for developing a hydraulic pressure sufficient to extend said packing means; first control means including first passage means interconnecting said pressure-developing means and packing means and first valve means in said first passage means for admitting hydraulic pressure to said packing means but preventing release of hydraulic pressure therefrom; and second control means including second passage means interconnecting said pressure-developing means and packing means, second valve means in said second passage means, and actuating means between said second valve means and mandrel responsive to movement of said mandrel toward said first active position for closing said second valve means and responsive to movement of said mandrel into said inactive position for opening said second valve means to release hydraulic pressure from said packing means.

4. The well tool of claim 3 further including second piston means fluidly sealed in said housing and slidable in response to movement of said mandrel toward a second one of its said active positions for developing a hydraulic pressure suflicient to extend said packing means, and wherein said actuating means are responsive to movement of said mandrel toward either of said first and second said active positions for closing said second valve means and responsive to movement of said mandrel into said active position for opening said second valve means to release hydraulic pressure from said packing means.

5. The well tool of claim 3 wherein said pressure-responsive packing means include a member having a pistion portion telescoped within one end of said housing and fluidly sealed thereto and an exposed portion including abutment means spaced from said housing end, a sleeve telescoped around an intermediate portion of said member, an annular expansible packing element around said member and between said abutment means and sleeve, and means fluidly sealing said sleeve to said housing and member for defining an enclosed space between said sealing means and piston portion into which said passage means connect.

6. The well tool of claim 3 wherein said second valve means includes a valve seat, a valve member movable into and out of seating engagement with said valve seat; and said actuating means is aligned with said valve' member and valve seat and adapted to engage and shift-said valve member into seating'engagement'with said'valve seat, cam means between said actuating means and-mandrel for shifting said actuating means toward said valve member in response to movement of said mandrel-toward said active positions and freeing .said actuating means for movement away from said valve member;-and biasing means normally urging said actuating means away from said valve member.

7. The well tool of claim 6 wherein said actuating means includes first and second members aligned with said valve member and valve seat, said first member having one portion adjacent to and adapted to engage and shift said valve member into seating engagement with said valve seat and another portion extending toward said second member, said second member having one portion with an enlarged portion extending toward said first member and a reduced portion between said enlarged portion and the remainder of said second member, and a retainer loosely disposed around said reduced portion adapted to engage said other portion of said first member; and wherein said biasing means includes a spring member between said retainer and said remainder of said second member.

8. The well tool of claim 3 further including pressureresponsive anchoring means on said housing and movable relative thereto from a retracted position to an extended position upon application of hydraulic pressure thereto; and third passage means interconnecting said anchoring means to said other passage means.

9. The well tool of claim 8 further including second piston means fluidly sealed in said housing and slidable in response to movement of said mandrel toward a second one of its said active positions for developing a hydraulic pressure sufficient to extend said packing means and anchoring means, and wherein said actuating means are responsive to movement of said mandrel toward either of said first and second active positions for closing said second valve means and responsive to movement of said mandrel into said active position for opening said second valve means to release hydraulic pressure from said packing means and anchoring means.

10. The well tool of claim 9 wherein said third passage means are connected to said other passage means between said valve means and said pressure-developing means.

11. The Well tool of claim 9 wherein said third passage means are connected to said other passage means between said valve means and said packing means.

12. The well tool of claim 9 wherein said pressure-responsive packing means include a member having a piston portion telescoped within one end of said housing and fluidly sealed thereto and an exposed portion including abutment means spaced from said housing end, a sleeve telescoped around an intermediate portion of said member, annular expansible packing means around said member and between said abutment means and sleeve, and means fluidly sealing said sleeve to said housing and member for defining an enclosed space between said sealing means and piston portion into which said passage means connect.

13. The well tool of claim 9 wherein said inactive position is intermediate of said first and second active positions, said piston means are first and second annular piston members respectively slidably disposed around and fluidly sealed to said mandrel; and further including first and second spaced opposed means on said mandrel adapted to engage and shift their associated piston members as said mandrel respectively moves toward either of said first and second active positions.

14. The well tool of claim 13 further including means coupling said mandrel to said housing for securing said 1 9 mandrel in said second position in one angular position relative to said housing and for freeing said mandrel for longitudinal shifting between said first and third positions in other angular positions relative to said housing.

15. The Well tool of claim 14 wherein said pressureresponsive packing means include a member having a piston portion telescoped within one end of said housing and fluidly sealed thereto and an exposed portion including abutment means spaced from said housing end, a sleeve telescoped around an intermediate portion of said member, annular expansible packing means around said member and between said abutment means and sleeve, and means fluidly sealing said sleeve to said housing and member for defining an enclosed space between said sealing means and piston portion into which said passage means connect.

References Cited UNITED STATES PATENTS 3,298,441 1/1967 Young 166-182 X 3,305,022 2/1967 Kisling 166122 3,306,361 2/1967 Lebourg l66122 3,308,882 3/1967 Lebourg 166-182 X 10 3,319,718 5/1967 Grafi 166226 X CHARLES E. OCONNELL, Primary Examiner.

DAVID H. BROWN, Examiner. 

2. A WELL BORE TOOL SIZED AND ADAPTED FOR RECEPTION IN A WELL BORE COMPRISING: A TUBULAR HOUSING; PRESSURE-RESPONSIVE PACKING MEANS INCLUDING A MEMBER HAVING A PISTON PORTIONS; PRESSURE-RESPONSIVE ANCHOR MEANS ON SAID FIRST MEMSEALED THERETO AND AN EXPOSED PORTION INCLUDING ABUTMENT MEANS SPACED FROM SAID HOUSING END, A SLEEVE TELESCOPED AROUND AN INTERMEDIATE PORTION OF SAID MEMBER, ANNULAR EXPANSIBLE PACKING ELEMENT AROUND SAID MEMBER AND BETWEEN SAID ABUTMENT MEANS AND SLEEVE, AND MEANS FLUIDLY SEALING SAID SLEEVE TO SAID HOUSING AND MEMBER FOR DEFINING AN ENCLOSED SPACE BETWEEN SAID SEALING MEANS AND PISTON PORTION; A MANDREL MOVABLY DISPOSED WITHIN SAID HOUSING AND ARRANGED FOR MOVEMENT THEREIN BETWEEN SPACED POSITIONS; PRESSURE-DEVELOPING MEANS INCLUDING PISTON MEANS FLUIDLY SEALED WITHIN SAID HOUSING AND SLIDABLE IN RESPONSE TO MOVEMENT OF SAID MANDREL TOWARD ONE OF ITS SAID POSITIONS FOR DEVELOPING AN INCREASED HYDRAULIC PRESSURE; AND PASSAGE MEANS INTERCONNECTING SAID PRESSURE-DEVELOPING MEANS AN SAID ENCLOSED SPACE. 